Narada 12REXC70, 12REXC200, 6REXC300 Operation Manual

LEAD-CARBON BATTERY

OPERATION

MANUAL

Version：V1.0

NARADA POWER SOURCE CO., LTD

12REXC Series

Narada Power Source Co., Ltd. 12REXC operation manual V1.0

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Content

Safety and Warning ......................................................................................................... 3

Chapter One Introduction of 12REXC series ............................................................... 4

1. Product Characters .............................................................................................. 4

2. Main applications ................................................................................................. 5

3. Configuration ....................................................................................................... 5

4. Types and Dimensions ......................................................................................... 6

5.Lead Carbon Working Principle ......................................................................... 6

Chapter Two Technical characteristic ............................................................................ 7

1. Discharge Curve and Discharge Data ................................................................ 7

2. Charge Curve ....................................................................................................... 8

3. Internal Resistance and Short-Circuit Current ................................................ 8

Chapter Three Operation and Maintenance ................................................................. 8

1. Parameters Setup ................................................................................................. 8

2. Capacity and Influence Factor ......................................................................... 10

3. Ambient Temperature vs. Battery .................................................................... 10

4. Requirement for Charge ................................................................................... 13

5. Storage ................................................................................................................. 16

6. Maintenance ....................................................................................................... 16

After-sales Service / Customer Service Hotline ........................................................... 17

Annex 1 ........................................................................................................................... 18

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Safety and Warning

Please read this manual! It provides very important direction for fix and operation, which can
make best capability for the equipment, and elongate the using life.
 For your safety, please do not try to dismantle or open the equipment. The equipment does

not contain any spare parts for you. The maintain work can only be done by specially
trained service persons.

 As a result of the batteries’ latent endanger to health and environment, they should be only

changed in our authorization service center. If you need to change the battery or maintain
the equipment, please call the nearest service center.

 Batteries can be reclaimed, if it could not be carefully handled, it will do great harms to

environment and heath. Please check local laws and regulations to get the validity handle
ways or send the equipment to authorized service center.

 The replacement of battery can only be done by persons who know well about the danger

and the prevention. When changing the battery, please use the same model and type of
sealed lead acid battery.

Warning—do not smoke or use fire near batteries

Warning—do not use organic solvent to wash batteries

Warning—dot not put batteries into the fire, or it may bombed
Warning—do not open batteries, it contains electrolyte, which can hurt the skin and eyes.
Warning—There may happen shock or short circuit when replacing the batteries. Please

operate with tools with insulated handles.

Please take care of the following marks in using

Warning

Electricity

danger

Protecting

your eyes

Watch

Short-circuits

With adults

custody

Do not put batteries

into dustbin

Read the

manual

Fire

forbidden

Circle used

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Chapter One Introduction of 12REXC series

12REXC series battery is designed for renewable energy sources such as wind power
and solar system, and developed for home energy system with long life, high energy
efficiency, superb security and reliability characteristic, which can be applied to energy
storage system, telecom and generator, etc.

1. Product Characters

 Lead carbon battery add carbon material with high capacitance or highly

conductive into the negative electrode, combine the advantages of lead acid
battery and super capacitors, lead carbon battery provide not only high energy
density, but also high power, rapid charge and discharge, longer cycle life.

 Combine the advantages of lead acid battery and super capacitors
 Ideal for PSOC cycle application
 Excellent recharge acceptance performance, super fast charge/large discharge

performance

 Reduce sulfation of the negative plate, longer cycle life

1.1 Design life is above 20 years

Grid alloy with special patented formula
Special patented negative paste formula
4BS paste technology
Extra-thick plate design

1.2 Initial capacity above 100%, the remaining capacity above 90% when storage for 3
months (25ºC)

1.3 Remarkable high rate discharge performance.

Low internal resistance. Patented grid design. Large section copper structure

1.4 Innovation patented lead carbon technology

The innovation patented lead carbon technology can solve sulfation of the negative
plate when used underfilling; compare with tradition VRLA battery, cycle life of the
lead carbon battery can be extended 3-10 times

1.5 Ideal for PSOC cycle application

Cycle use at 80% SOC (part state of charge) can be longer PSOC cycle life, which
especially designed for solar or wind energy storage system

1.6 Supply the unique flexible connectors made of rubber wrapped with copper wires
and another option is copper bar connector.

Assure the good connections of post and connectors and low connection resistance;

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Combination of suppleness and rigidity for more flexible connections;

1.7 Flexible and convenient installation, slinky outside looking

Shockproof blocking assembling

Satisfy customer’s individual requirements and provide up to 8-class shockproof

Streamline and dime-light battery outside-looking design.

2. Main applications

 Home energy storage system
 Hybrid energy system such as solar and wind energy
 Distributed energy storage system
 Smart power grids and microgrids system
 Generator and battery hybrid energy system
 Solar power generation grid/off-grid energy storage system
 Emergency lighting system
 Other standby, cycling system

3. Configuration

Fig. 1-1 Configuration

Lid

Pole

Container

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4. Types and Dimensions

Table 1-1 type specifications

Battery Type

Rated
Voltage
per cell
(V)

Rated Capacity (Ah)

Dimensions (mm)

Weight

(Kg)

C10

C

100

Length

Width

Height

Overall

Height

End-volta
ge

1.80V

End-volt

age

1.85V

12REXC70

2

60

70

280

180

230

244

30

12REXC200

2

165

200

438

227

281

294

79.5

6REXC300

2

250

300

338

227

281

294

61

5.Lead Carbon Working Principle

Fig.1-2 Lead carbon battery working principle sketch map
It forms a new active center in negative electrode by adding active carbon, that can
reduce lead deposition overpotential, the lead sulfate will be translated into lead more
easily. Growing up of lead sulfate can be suppressed efficiently through this
technology.

Fig.1-3 Lead carbon negative electrode surface current distribution sketch map

The chemical reaction taking place in lead carbon battery is as follows:
positive electrode:

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negative electrode:

Because of the reaction is based on double layer capacitance which caused from
carbon electrode/electrolyte interface, thereby the lead carbon battery has part
characteristic of super capacitors. Thus the lead carbon battery can possess large
current and long cycle life performances.
12REXC battery adopts a design of barren-liquor and utilizes AGM (micro porous
glass fiber) separator. Thus there is a path existing between the positive and the
negative. Also special alloy grid is chosen to increase vent hydrogen over-potential
gassing on the negative plate, which prevents generation of hydrogen. Otherwise, the
oxygen generated from positive diffuses through separator to the negative and the

oxygen gas reacts quickly and is recombined into water. The reactions are as follows:：
2Pb +O2 2PbO ;

PbO+ H2SO

4

PbSO4 +H2O;

So it is possible to build 12REXC battery in sealed structure.

Chapter Two Technical characteristic

1. Discharge Curve and Discharge Data

Fig. 2-1 12REXC Battery Discharge Performance Curves at Different Discharge Rates

（25℃）

Discharge curve at different rate 25（ ℃）

1

C120C10

C3

C1

Discharge voltage V（ ）

HoursMin

13.20

12.00

10.80

9.60

8.40

O(l)2H(s)PbSO

arg

arg

2(aq)3H(aq)HSO(s)PbO

24

-

-

42





ech

edisch

e

-

2-x

2)-(x

6x

x
6

2e (aq)2H(aq))(HnC

arg

arg

(aq))(HnC

--





ech

edisch

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Fig.2-1 Discharge characteristic curve

2. Charge Curve

Fig.2-2 Recharge characteristics of 12REXC battery with current of 0.1C10A and limit
voltage of 2.30V/cell (25℃). The 100% DOD battery can be recharged 105% of
capacity after charging for 24 hours. Imaginary line is the recharge curve of 50%DOD.

Charge curve 25 ( ℃ )

14.1

13.5

12.9

12.3

100% disc harge

50% discharge

0 244 1612 208

C harge capacity(%)

C harge current(C A)

C harge voltage(V )

Charge current

Charge capacity

Charge voltage

Time ( h )

Fig.2-2 Charge characteristic curve

3. Internal Resistance and Short-Circuit Current

The internal resistance of the battery is a dynamic nonlinear parameter that is
continuously changed along with the temperature and discharge state. The internal
resistance is the lowest when battery is fully charged. The table 2-3 shows the internal
resistance and short circuit current of 12REXC battery in fully charged state according
to the IEC60896 standard. Pay attention to the battery to short-circuit causes the
battery voltage to reduce to 0V, and will cause the battery internal component
damaged.

Table 2-3 Referenced Internal Resistance and Short Current

Battery Type

Internal Resistance

(mΩ)

Short Current (A)

12REXC70

9.79

1291

12REXC200

3.83

3274

6REXC300

1.35

4619

Chapter Three Operation and Maintenance

1. Parameters Setup

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Table3-1 Home energy storage system parameter setup table (48V system)

Parameter name

Unit

Grid

Off-grid

Floating Voltage per cell

V/cell

2.30

2.30

Equalization Voltage per cell

V/cell

2.25

2.25

Charging Current

A/cell

0.1C10

0.2C10

Discharge under-voltage protection

per cell

V

Please refer to table 3-2

Condition To Change Equalization

Charge To Float Charge

mA/Ah

＜5

＜5

Condition to Change Float Charge To

Equalization Charge

mA/Ah

＞50

＞50

Pack equalization voltage

V

55.2

55.2

Pack floating voltage

V

54.0

54.0

Pack charging current

A

0.1C10

0.2C10

Pack discharge under-voltage

protection

V

Please refer to table 3-2

Temperature Compensate Ratio With

Floating Voltage

mV/℃ /

cell

-3

-3

Temperature Compensate Ratio With

Equalization Voltage

mV/℃ /

cell

-5

-5

High Temperature Warning

℃

35

35

Short circuit protection current

A

Please refer to table 3-2

1. The voltage in above table is at 25℃. Please adjust the data according to table 3-3 at
other temperature.

2. Energy storage system can be off-grid power supply and grid power supply
according to real situation. The off-grid defined as tough power supply, to protect the
battery better, please set refer to above table or contact to manufacture.

3. Above are standard setup parameters in table 3-1. We suggest you to set up end
voltage (LVBD) based on different load current to make the battery life longer. Please
refer to table 3-2.

Table 3-2 Voltage setup parameter of LVBD and LVLD

Load current（A）

End voltage（V/cell）

LVBD for 48V system

（V）

I＜0.025C10

1.97

47.3

0.025C10≤I＜0.05C10

1.92

46.1

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0.05C10≤I＜0.1C10

1.87

44.9

0.1C10≤I＜0.2C10

1.83

43.92

0.2C10≤I＜0.5C10

1.75

42.0

If the battery is not recharged in time after discharge, or the power is off again during
recharge, the insufficient-charged batteries will be frequently discharge, thus the
batteries will lose part of capacity in short period. And it may cause capacity loss at
initial stage and the batteries will be rejected if the situation is serious.

2. Capacity and Influence Factor

The capacity of battery is the capacity that battery can be discharged in the established
conditions, expressed as signal C. The usual unit of capacity is ampere-hour, shortened
as AH. The rated time is marked in the right and low corner of C, i.e. C10 is the
capacity at 10 hours rate; C3 is the capacity at 3 hours rate.
The capacity can be expressed in Rated Capacity or Actual Capacity. For Rated
Capacity of 12REXC, please see Table 1-1. The Actual Capacity is the actual output
capacity in certain discharge conditions, which is equal to product of the discharge
current and the discharge time, the unit is AH. The actual capacity is effected by
discharge rate, discharge mode, end voltage and temperature.

3. Ambient Temperature vs. Battery

The recommendation temperature for 12REXC is 15 ℃ ~ 25 ℃. Used at high or low
temperature, battery performance will be affected. Table 3-3 is the working
temperature range for battery.

Table 3-3 Working temperature range for battery

Working condition

Temperature range

Recommended temperature

Discharge

-40℃～50℃

15℃～25℃

Charge

-20℃～50℃

15℃～25℃

Storage

-20℃～40℃

15℃～25℃

Temperature affects capacity of the battery. Fig. 3-1 is the available capacity (10h rated,
end voltage 1.80Vpc) curve vs. ambient temperature. When the temperature is low, the
capacity will decrease, for example, the capacity will decrease 10% if temperature
decreases from 25 ℃ to 0℃; And too low temperature will cause battery long term
insufficient charged, also will make negative plates sulfate and make battery unable to
discharge.
The capacity will increase at some range when temperature rises. For example the

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capacity will increase 5% if temperature raises from 25℃ to 35℃. But when the
temperature go up further, the capacity will increase slowly, and at last stop increasing.

However, high temperature will quicken up plates’ corrosion and cause water loss, thus

shortens battery’s life.

Fig.3-1 Available Capacity Curve VS. Ambient Temperature

3.1 Temperature and Floating Voltage, Equalization Voltage

The purpose to select certain floating voltage is make the battery operate in best
conditions. If the floating voltage is higher, the floating current is also higher; it will
accelerate the corruption of grids and shorten the life of the battery. If the floating

voltage is lower, the battery can’t be kept in fully charged state, this will crystallize

PbSO4, decrease the capacity, and also shorten the life of the battery. At 25℃, the
floating voltage is 2.25V, at other temperature, please adjust according to Table 3-4.
The temperature compensation coefficient for float charge is -3mV/℃/cell. Valve
regulated sealed lead acid battery need to be equalized charge regularly, in order to
guarantees the battery normal operation. 12REXC battery’s equalization voltage is

2.30V/cell.

Capacity %

Ambient Temperature（℃）

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Fig. 3－2 The Voltage Setting Curve Vs. Ambient Temperature

If the voltage lower than 2.225 or higher than 2.35 after temperature correction, the suggesting
adopted can be charging by 2.25V or 2.35V directly without using temperature compensation.

Table 3-4 Relationship of ambient temperature and voltage

Ambient Temperature(℃)

Equalization Voltage(V/cell)

Float Voltage(V/cell)

≤15

2.350

2.275

20

2.325

2.260

25

2.300

2.245

30

2.275

2.230

35

2.250

2.215

≥40

2.225

2.200

3.2 Ambient temperature vs. Battery Life
The high temperature will damage the battery, reduce the battery life. When
temperature exceeds 25℃, the battery life will decrease half per 10℃ temperature
raise. For example, the design life of battery is 20 years at 25℃, if the battery is
operate at 35℃ for long term, the life will be 10 years. Below is the formula:

L25＝LT×2

（T－25）

/10

Notes：T is the actual ambient temperature;

Floating and equalization setting voltage at different temperature

Voltage (V)

Temperature (℃)

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LT is designed life at T ambient temperature

L25 is designed life at 25℃ ambient temperature
Ambient temperature elevating, also will accelerate the battery grids corrosion and the
battery water loss, thus will greatly reduce the battery life. So it is important to control
the ambient temperature. When heat is accumulated to a certain degree, it will damage
the battery, seriously will lead to thermal run away. If indoor temperature reaches too
high, please improve the ambient temperature by making room ventilated, etc. The
battery spacing cannot to be less than 10mm, at the same time regulating cell floating
and equalization voltage value according to handbook’s request.

3.3 Conductance, Resistance vs. Capacity
There is a certain corresponding relationship between conductance & resistance and
battery capacity. We suggest to test battery conductance and resistance data at different
stage with same type instruments from same factory. Conductance and resistance data
is only a reference to judge whether battery is good. These data cannot replace loading
test to judge whether battery is good. Narada recommend to test these data on the
surface or side of battery post. If there are several pairs of post, please test on nearest
pair of post.

Figure 3-3 Test location for conductance and resistance

4. Requirement for Charge

4.1 Periodically Equalization Charge

The battery needs an equalization charge after floating operation over three months, or

the voltage of at least two batteries are lower than 2.17V. The method of equalization

charge is constant current and limited voltage, as follows: charge with constant current

of 0.1C10A～0.15C10A till the average voltage reaches equalization charge voltage of

2.30Vpc (25℃), then keep charging with equalization charge voltage, meanwhile, the
current is reduced, till the charge finished. The charging time is 24 hours.

Test location for

conductance and

resistance

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4.2 Charge after discharge

After discharge, the batteries should be charged in time. The charge method is
constant current limit voltage as follows: charge with constant current of

0.1C10A～0.20C10A till the average voltage reaches a certain voltage, then keep
charging with this voltage, meanwhile, the current is reduced, till the charge

finished.
The certain voltage could be equalization voltage or float voltage. When the depth
of discharge is larger (normally larger than 10%), equalization voltage is
recommended so as to give fully charge to the battery. We can also determine
charge voltage according to initial current. When the current is larger than

0.05C10A (reference current to change to equalization charge), equalization
voltage is recommended. The charge time is 24 hours. We can also setup the
charge voltage according to different DOD, different charge current shown in
figure 3-4, or we can judge according to charge current value.

Normally, the batteries are fully charged when the value of charge current is not
changed for continuous three hours at the stage of constant voltage charge,

Sometimes, we need to charge a battery in a short time, we can raise charge
current, but not higher than 0.25C10A.

Fig .3-4 The relationship between DOD and charge time

4.3 Battery recharging method
This method is used for battery charging for the first time after installing or battery

recharging after long time storage.
 Recharging parameter

We use equalizing charge to recharge the batteries, the parameter is as below:
1 Charging mode: equalizing charge;
2 Charging voltage: (2.30±0.002)V/cell;

Charge

time(h)

Depth of discharge (DOD %)

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3 Charging current limited: 0.05C10A;
4 Cut-off condition: the charging current is less than 0.005C10 with another

extended 3 hours or charging time reached 24 hours (alternative);

 Recharging procedure

1 Connect the batteries in series with cables or copper bars, and make sure that all
the screws tightened with each joint, then connect the anode of battery group to the
anode of charging equipment (charger), and the cathode of battery group to the
cathode of charger.
Pay attention: A breaker or fuse should be connected in the circuit in order to
protect the batteries and charger, the capacity of breaker or fuse should be 1.5
times of circuit maximum current.
2 Turn on the charger, set the charging voltage and current according to 4.1
recharging parameter.

3 Turn the breaker or fuse, and then turn on the charger to recharging batteries.
4 Stop charging when reaching the cut-off condition. At the last one hour before

finishing, test the battery voltage one by one, the battery which voltage is below

2.16V/cell should be dealt with the method in chapter 3.3, if that battery can not
accord with the requirement, it should be rejected.

 Cycle procedure

We can use the method as below to recharge the batteries after long time storage
(for example: more than 1 year):
First connect the batteries in series to the charger, discharge batteries with constant
current 0.25C

10

(A) for about 3 hours. Then use the method above to charge the
batteries. Stop charging when reach the cut-off condition.
If the capacity still can not be renewed by this method, this means the batteries fail
because of long time storage or other reasons.

4.4 Maintenance of wind/solar generating energy storage system
It is necessary to recharge one time every two months for maintenance because of the
under-filling state of the batteries used in home energy storage system and wind/solar
generating energy storage system. The battery maintenance method can operate as
below:
In the case of mains supply, the maintenance and battery recharge methods be the same
as clause 4.1.

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In case of without mains supply, should cut off the load, then the solar and wind
generating can charge the battery, but maximum limited voltage 2.30V/cell, maximum
current 0.20 C

10

A. The battery fully charged on condition that the charging current is

less than 0.005C10 or the charging voltage stay constant for four hours.

5. Storage

The storage area of 12REXC series batteries must be clean, ventilated, dry and without
direct sunshine. All lead acid batteries lose capacity when standing on open circuit
because of self-discharge. The result is that the voltage of open circuit is decreased,
and the capacity also decreased. The self-discharge rate is related with ambient
temperature. The self-discharge degree is smaller when the ambient temperature is
lower, otherwise is larger. Batteries should be supplementary charged if they have been
stored for six months or the open circuit voltage is lower than 2.10V/cell. The
equalization charge method should be adopted. All batteries, which are ready to store,

should be fully charged before storage. It’s suggested to record storage time in periodic

maintenance record and record the time when another necessary supplementary charge
should be made. The quality certificates of 12REXC series batteries record the latest
charge time of the batteries, next charge time can be calculated according to this charge
time.

6. Maintenance

In order to assure service life, the batteries should be correctly inspected and
maintained. The maintenance methods of 12REXC batteries are recommended as
follows:

6.1 Monthly Maintenance

— Keep the battery-room clean.
— Measure and record the ambient temperature of the battery-room.
— Check each battery’s cleanness; check damage and overheating trace of the

terminal, container and lid.

— Measure and record the total voltage and floating current of the battery system.

6.2 Quarterly Maintenance

— Repeat monthly inspection.
— Measure and record floating voltage of every on-line battery. If more than two

cells’ voltage is less than 2.18Vpc after temperature compensation, the

batteries need to be equalization charged.

6.3 Yearly Maintenance

— Repeat quarterly maintenance and inspection.
— Check whether connectors are loose or not every year and tight them
— Make a discharge test to check with exact load every year, discharging 30-40%

of rated capacity. Make an 80%DOD capacity test every year after three years’
operation.

6.4 Operation and Maintenance Precautions
Insufficient Charge

If the floating voltage is not set correctly (too low or not compensate according to

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temperature), the battery system will in an insufficient charge state for a long
period of time. When the electricity is out, the battery may not be able to work
because the acid is satirized and the capacity is decreased.

Over Charge

If we neglect the performance of rectifier to transfer floating charge to equalization
charge. If the rectifier cannot transfer charge modes because of its wrong
performance or no adjustment, the battery system is always in an equalization
charge state. Thus may cause serious problems for battery, such as water loss, life
decrease, thermal runaway, deformation, etc.

Too low or too high temperature

We have mentioned that too low temperature will affect the capacity of battery.
While too high temperature will also cause problems, such as water loss, life
decrease, thermal runaway, deformation, etc.

Too low end voltage

The end voltage is also an important parameter for battery. The battery shall stop
discharge when reach a certain voltage (The normal end voltage is 1.8Vpc for 10
hours rated). If the end voltage is too low, it will be difficult to recharge the battery
and decrease the charge efficiency, thus reduce the life of battery.

Long time storage after discharge

If the battery is put aside without charge for a long time after discharge, it will
affect the capacity and life of the battery, because some large size PbSO4 will be
created in the negative, which are difficult to transfer to active Pb. Thus it will
affect battery life and capacity

After-sales Service / Customer Service Hotline

P.R. China: Asia Pacific:

Narada Power Source Co., Ltd.

9F, Building A, No. 50 Zijinghua Road,
Hangzhou, China
Tel: [phone]
Fax: [phone]
E-mail: [e-mail]
Website: www.naradabattery.com

NARADA ASIA PACIFIC PTE.LTD.

65 Ubi Crescent #07-05 Hola centre,
Singapore
Tel: [phone]
Fax: [phone]
E-mail: [e-mail]

12REXC series operation manual

– (V1.0

–N- EN August 2014)

– Subject to revisio

n without prior

notice E.&O.E.

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18

Annex 1

VRLA Battery Regular Maintenance Record

Type Place

Status

Number of battery

Total Voltage（V）

Current (A)

Temperature

No.
Voltage（V）

No.
Voltage（V）

1 13

2 14 3 15

4 16

5 17

6 18 7 19 8 20 9 21 10 22 11 23 12 24 Check by sight

Result:

Tester:

Date: